This precision speed control was obtained in an Electronic Design from the 90's. The output final stage power transistors must be in accordance with the motor power.
We found this simple transistor tester in a French publication in 1981. It uses a common analog...
Who is faster? or reaction game are other names for this circuit that we find in old...
This circuit is from an 80's component manual. The components are from the time, but the circuit...